Underfeed stoker



E. J. HART UNDERFEED S TOKER Filed 0G11. 2O 1921 5 ShQetS-Shee 1 JNVENTOR. Y MWQMZJ ATTORNEY.

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UNDERFEED STOKER Filed oct. 20. 15.321

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E. J. HART UNDERFEED sToKER 5 sheets-sheet 5 Filed Oct. 2O 1921 INVENTOR. ,dmfddff A TTORNE Y.

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Application led October 20, 1921. Serial No. 508,988.

' lTo all ibhom t may .cof/wem.' l

Be it known that I, EDWARD J. -I-IART, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and Stateof Pennsylvania, have invented new and useful Improvementsin Underfeed Stokers, of which the following is a specication.

invention relates to a new and useful improvement in underfeed stokers, and is a continuation in part of my co-pending application, Serial Number 370,651, dated April 2nd, 1920, and primarilyhas for its object to so feed the fuel to the fire bed as to brin about a complete distribution of the fue and to produce a high efficiency in the combustion thereof, this vresult being accomplished by providing amain retort beneath the fire bed, branch or secondary retorts leading from the main retort, and means for feeding the fuel to the main retort, and also means for feeding fuel from the main retor`t to the secondary retorts and from the latter to the fire bed.

A further object of my invention is. to provide reciprocating grate bars so constructed and arranged as to give the fuel of the fire bed a gradual movementl outward from the main conduit.

A still further object of my invention is to provide a three-zone air system for properly feeding the air under different pressures to the different zones of the fire bed.

With these and other ends in' view, this invention consists in the details of construction and combination of elements hereinafter set forth `and then specifically designated by the claims.

In order that those skilled in the art to which this invention appertains, may understand how to makeand use the same, I will describe its construction in detail, referring by numerals to the accompanying drawings forming a part of this application, in which:-

Fig. 1, is a front elevation of a boiler or like furnace showing the operating mechanism of my improved Stoker. f

Fig. 2, is a plan view of a part of the interior of a furnace equipped with my improved stoker and illustrating the relation of the hopper and feeding mechanism thereto, said hopper and mechanism beingon the exterior of the furnace.

,Figp 3, is a section at the line 3-3 of 2. ig. 4, is a section at the line 4 4 of Fig. 2.

Fig 5, is a section at the' line 5-5 of Flg. 2. Fig. 6, is a detail 1an view of the operatinmechanism for t e ash shelves. F' ig 7, 1s a section at the line 7-7 of Fig. 8, is a central longitudinal section of one of the grates.

Fig. 9, Vis a side elevation of one of the grates. Fig. 10 is an end view of the plunger and 1ts connected pusher rod.

Fig. 11 is a .side elevation thereof with a part of the pusher rod broken away.

In carrying out my invention as here em.-

bodied, l represents the furnace, the walls of whichmay be of any suitable construction, and within this furnace is located a main retort 2 here shown as extending through vthe center thereof below the level of the grate surface. From this main retort extend the secondaryretorts 3 which latter maybe ar' ranged in two sets, one set on each side of the main retort and the bottoms of said secondary retorts are on a lower level than the bottom of the main retort. The secondary retorts have spaces therebetween for the po sitioning of the gratesi, these grates having the flanges 6 adapted to ride upon the upper edges of the retorts which are inclined as indicated at 5 so thatwhen the grates are reciprocated outwardA they will have a sli ht upward movement for the purpose heremafter described.

Each of the grates is constructed in the form of steps, each step having two side walls converging toward each other terminating in an apex, and in these side walls are located the draught outlets 7; also each of these grates has a hollow head 8 through which the draught openings 9 are formed, A

and between adjacent grates is located a hollow head 10 which corresponds to the shape of'th'e heads of the grates, thus forming a jecting between the lugs 13 and 14 formed upon the grates so that` as these shafts are rocked each set of grates will be given a limited outward and inward movement to and from the main retort. y

These rock Yshafts extend through the front Wall of the furnace and have the levers 15 secured on their outer ends, each lever carrying a stud 16 with which the slotted end of one of the connecting rods 17 isV adapted to engage 18 represents the actuatingbars their outer ends being fitted to slide 1n the bearings 19, while their inner ends are fitted to slide in the bearings 20, and these bars are reciprocated by the crank wheel 21 to which they are connected by the pitmen 22. n

23 represents a hopper for the reception of the fuel to be fed to the furnace and beneath this hopper is located an open end cylinder 24'in which reciprocates the plunger 25, said plunger being connected by theppitman 26 with the crank 27 secured upon the upper end of the shaft 28. This shaft has secured thereon a bevel gear 29 which meshes with the bevel gea-r 30 the latter being secured upon the -main shaft 31, on which latter is also mounted the crank wheel 21. A housing 310 is provided for the driving gearing and houses portions of the last mentioned shafts. .The plunger 25 carries a depending lug 32 which projects through a suitable slot formed in the open end cylinder,and to this lug is adjustably attached the pusher rod 33 upon which latter a-re secured the pusher blocks 34 the heels of which are beveled as indicated at 35 in order to facilitate their backward movement through the fuel. By the construction just described the reciprocating of the plunger 25 beneath the open bottom of the hopper 23 will feed the fuel from the hopper to the main retort and the pusher blocks 34 movin in unison with the plunger 25 will assist in moving said fuel engthwise of said retort as will be readily understood.

In order that the fuel may be fed from the main retort to the secondary or cross retorts, I provide open end cylinders or casings 36 arranged beneath the main retort the latter communicating with said cylinders through the openings 37, and within each of the cylinders 36 is fitted a plunger 38 adapted to slide to and fro therein, andv one of the open ends of each of these cylinders communica-tes with one of the secondary retorts in one of the series thereof whileplungers are moved to and fro the fuel flowing downward from the main retort to the cylinders 36 will be ejected from said cylinders in one direction` and then the other beinguforced into the secondary retorts. As the to the secondary retorts it will gradually travel outward and then upward upon the inclined bottoms- 3a of the secondary re gradually elevated to torts 3 and thus be the fire bed.

The plungers 38 Aare secured u on the rods l39,-which`extend through suita le bearin s el is thus fed from the main retort which are connected by the notched links 45 with the actuating bars 18 by engaging with the studs 46 and 47. Thus when the actuating bar is being reciprocated as-before described the plungers 38 will be moved to and fro.

Upon the main shaft 31 is secured a worm ear 48 with ,whichmeshes the worm 49 the a-tter being secured upon the drive shaft 50adapted to receive power from any suitable source, and I prefer that the worin gear, Worin and bevel gears be enclosed in a suitable oil tight casing 51 for the proper lubrication. The object of utilizing the connecting rods 17 and notched links 45 is to provide for the pro er adjustment of the actuating bars 18 and the position of the levers 15 relative to said actuating bars which is readily accomplished by substituting links of different lengths.

Beyond the outer ends of the grates 4 are located the ash shelves 52 which are secured to the shafts 53 in any suitable manner, and these shafts extend through the front wall of the furnace and have secured thereonthe bevel gears 53a which mesh with the bevel gears 54 the latter being secured upon the short shafts 56 carrying the handle bars 57 by the manipulation of which'latter the ash shelves may be swungdownward so as to dump the ashes therefrom into the ash pits 58. A suitable ratchet wheel 59 is fixed to each of the short shafts 56 with which coacts a pawl 59 for holding the ash shelves in their horizontal positions when set.

In order that air may be admitted to different zones of the lire bed under different pressures I divide the space beneath the retorts and grates into three zones, the first zone or that in which the air is-under the initial pressure consisting of the main duct 60 and the space beneath the main retort 2, the second zones being represented by the spaces 61 beneath the secondary retorts and grates, while the third zones are represented by the ash pits 58. Communication between the first and second zones is controlled by the slide doors or dampers 62 esl of the fire bed or that portion of the fuel being crowded upward from the main retort 2. The'air from the second zones the pressure upon which is determined by the proper regulation of the danipers 62 will flow upward to the interior of the grates and thence through the openings 7 in said grates to the llire bed resting upon the grates and being fed rearward and upward from the secondary retorts 3. The air from the third zones the pressure of which is determined by the proper regulation of the dampers 63 will flow upward through the ash shelves which are perforated for that purpose thus supplying draught under relatively low pressure for completing the combustion of any fuel which may still remain in the ash` deposited upon said shelves by the processes of feeding the fuel.

In my present invention the three-zone air feed is of great importance since the distribution of the fuel over the lire bed is such that the central portion thereof or that portion which is fed to the fire bed directed from the main retort 2 will be relatively of considerable depth and therefore requires a relatively high pressure of air to create the proper draught therethrough, while that portion of the fuel which is fed from the secondary retorts over the grates will be of less depth and therefore require less air pressure to produce the proper draught for eilicient combustion and finally the unconsumed fuel which may reach the ash shelves will offer less resistance to the passage of air and therefore under my system the air fed thereto is under little more than atmospheric pressure.

As it is desirable under some conditions to feed a. certain amount of air above the fire bed, I provide a branch duct 64 which leads from the main duct 60 to a point above the grate surface and is provided with a valve seat 65 which 'the valve seat 66 is adapted to close, said valve being carried by a valve rod 67 which passes out through the front wall of the furnace and-may terminate in a. handle for the proper manipulation of the valve. By this arrangement the valve 66 may be opened to permit a stream of air under pressure to be projected over the lire bed or this damper may be closed to shut off the inflow of air at this point as occasion may require.

Suitable doors 68 are provided for access to the space above the ash shelves to permit the stoking at these points; also suitable doors 69 are provided for access to the ash pits and likewise suitable doors 70 are provided for access to the underside of the grates to remove any fuel which may 'fall from the grates.

While my present invention may be variously modified to adapt it to varying condiexact details of construction as herein shown as these may be varied within the limits of the appended claims without departing from the spirit of my invention.

Having thus fully described my invention, what I claim as new and useful is l. In a stoker of the ,character described, the combination with a furnace, of a main retort located beneath the level of the fire bed, means for feeding fuel from the out-side of the furnace to and through said retort, secondary retorts extending laterally from the main retort in communication therewith, said secondary retorts also being located beneath the level of the fire bed, means for feeding fuel from the main retort to the secondary retorts, a series of grates located between adjacent secondary retorts, and means for reciprocating said grates.

2. In a stoker of the character described, the combination with a furnace, of a main retort located beneath the level of the fire bed, means for feedin fuel from the outside of the furnace toan throu h said retort, secondary retorts extending laterally from the main retort in communication therewith, said secondary retorts also being located beneath the level of the fire bed, means for feeding fuel from the main retort to the secondary retorts, a series of grates located between adjacent secondary retorts, means for reciprocating said grates, and ash shelves located at the outer ends of the grates.

3. In an under feed stoker,`a main retort located within a furnace and extending from the front to the rear thereof, means for feeding fuel to said retort, two sets of secondary retorts leading from opposite sides of the main retort and extending crosswise of the furnace, and means for feeding fuel from the main retort to the secondary retorts, and reciprocating grates disposed between adjacent secondary retrts.

4. In an under feed stoker, a main retort located within a furnace and extending from the front to the rear thereof, means for feeding fuel to said retort, two sets of secondary retorts leading from opposite sides of the main retort and extending crosswiseof the furnace, means for feeding fuel from the izo -- rearward movement of the fuel in sai main retdrt to the secondary retorts, reciprocating grates,edisposed between adJacent secondary retorts, and means for feeding a1r to the grates in zones vunder a different pressure for each zone'. I

' 5. In an under feed stoker, a main retort located within a furnace and extending from the front to the rear thereof, a set of secondary retorts located upon each side of the main retort and extendin crosswise of the furnace, cylinders located leneath the main retortl and communicating therewith, the ends of said cylinders communicat' with the secondary retorts, and a plunger ocated in each of the cylinders for feeding fuel from the main retort to the secondary retorts.

6. In an under feed stoker, a main retort located within a furnace and extending from the front to the rear thereof, a set of secondary retorts located upon each side `of the main retort and extendin crosswise of the furnace, cylinders locate beneath the main `retort and communicating therewith, the ends of said cylinders communicatin with the secondary retorts, a plunger locate in each of the cylinders for feeding fuel. from the main retort to the secondary retorts, rods upon which said plungers are mounted, levers connected with said rods for reciprocating the latter, rock shafts upon which said levers are secured, and means for rocking said shaft. v

7. In an under feed Stoker, a main retort located within a furnace and extendingpfrom the front to the rear thereof, a set of secndary retorts located upon each side of the main retort and extending crosswise of the furnace, cylinders located beneath the main retort and communicating therewith, the ends of said cylinders communicating with the secondary retorts, a plun er located in each of the cylinders for feedlng fuel from the main retort to the secondary retorts, and means for reci rocating said pllun er.

8. In an un er feed stoker of e character described, a main retort located'within a furnace and" extending from the front to the rear thereof, an open end cylinder located in alignment with the front endv of said retort, a hopper mounted upon said cylinder for feeding fuel thereto, a plunger adapted to reciprocate -in said cylinder for feeding fuel to the retort, a pusher rod adjustably attached to the plunger and extending lengthwise of the retort, pusher blocks` carried by'said rod for efectin the retort, a crank shaft, a crank secured thereon, a pitman connecting said crank and plun er in such manner as to reciprocate the atter, a bevel gear secured upon the crank shaft, a second bevel gear meshing with the first' named bevel gear, a main shaft upon which the second named bevel gear is with said rods cylinders -providing communication between4 the main and secondar' retorts, plun ers adapted to slide to and o in said cylin ers for feeding fuel from the main to the secondary retorts, rods upon which said plungers are mounted, 'forked levers connected for `actuatin the same, slhafts upon which the forked evers are secured, o erating levers secured upon the outer en s of the last namedjshaft, actuating bars, bearin s in which said bars are,

links for connecting the mounted, notche operating levers to the actuating bars, a

crank wheel carried by the main shaft, and

pitmen connecting said crank wheel with the Aactuating rodswhereby power is transmitted from the main shaft to the plungers.

9. In an under feed stoker of the character described, a main retort located within a furnace and extending from the front to the vrear thereof, an open end cylinder 1ocated in alignment wlth the front end of said retort, a hopper mounted upon said cylinder for feeding fuel thereto, a plunger adapted to reciprocate in said cylinder for feeding fuel to the retort, a pusher rod adjustably attached to the plunger and extending lengthwise of the retort, usher blocks carried-by said rod for eii'ectm the rearward movement of the fuel in sai conduit, a

crank shaft, a crank secured thereon, a pitthe main retort, cylinders providing com-l munication between the main and secondary retorts, plungers adapted to slide to and fro in said cylinders for feeding-fuel from the main to the secondary retorts, rods upon which said plungers are mounted, forked levers connected with said rods for actuating the same, shafts upon which the forked levers are secured, operating levers secured upon the outer ends of the last named shaft, actuating bars, bearings in which said bars are mounted, notched links for connecting the operating levers to the actuating bars, a crank wheel carried by the main shaft, pitmen connecting said crank wheel with the actuating rods whereby power is transmitted from the main shaft to the plungers, hollow perforated grates located between adjacent secondary retorts and adapted to ride over the edges thereof, shafts journalledbeneath the grates, projections on said shafts adapted to reciprocate said grates, operating 1evers secured to the outer ends of the last 5 named shafts, and notched links connecting these last named operating levers to the actuating bars whereby power is transmitted from said actuating bars to the grates.

10. In an under feed Stoker, the combinay 10 tionl with a furnace of a main retort from which extend branch retorts and movable grates between adjacent branch retorts.

1l. In an under feed Stoker, the combination with a furnace, of a main retort from which extend branch retorts and reciprocating grates located between adjacent branch retorts.

In testimony whereof, I have hereunto affixed my signature.

EDWARD J. HART. 

